The Cleo 98 occurrence is located on the eastern end of a ridge separating the arm of Mathew Creek, at approximately 1800 metres elevation.

Regionally, the area is underlain by argillite, greywacke, wacke and turbidites of the middle Proterozoic Aldridge Formation (Purcell Supergroup). These have been intruded by gabbroic sills of the middle Proterozoic Moyie Intrusions. A full description of regional geology can be found in the Sullivan (MINFILE 082FNE052) occurrence.

Locally, silty sandstone hosts disseminated pyrrhotite. In 1998, a sample (132205) assayed 0.265 per cent zinc and 2.6 grams per tonne silver (Assessment Report 25851).

In 1975, Cominco drilled on diamond drill hole, totalling 500.0 metres, on the Mat 169 claim to the north. In 1984, Cominco completed a further four diamond drill holes, totalling 747 metres, on the Mat claims. In 1996 and 1998, Abitibi Mining completed programs of rock and silt sampling, prospecting and geological mapping on the area as the Cleo and Clair claims.